1. Field of the Invention
The present invention relates generally to building materials and more particularly to materials used for sound insulation.
2. Background Information
In building modern structures, such as single-family houses or commercial buildings, an important factor to consider is noise control. In order to provide a quiet environment, sounds originating from sources such as televisions or conversation must be controlled and reduced to comfortable sound pressure levels. To achieve such an environment, builders and designers must address a multitude of factors, among them the construction and composition of building component assemblies that separate rooms from other rooms or from the outside environment. Such assemblies may, for example, take form as interior walls, exterior walls, ceilings, or floors of a building.
The term xe2x80x9ctransmission lossxe2x80x9d is expressed in decibels (db) and refers to the ratio of the sound energy striking an assembly to the sound energy transmitted through the assembly. A high transmission loss indicates that very little sound energy (relative to the striking sound energy) is being transmitted through an assembly. However, transmission loss varies depending on the frequency of the striking sound energy, i.e., low frequency sounds generally result in lesser transmission loss than high frequency sounds. In order to measure and compare the sound performances of different materials and assemblies (i.e., their abilities to block or absorb sound energy), while also taking into account the varying transmission losses associated with different sound frequencies, builders and designers typically use a single-number rating called Sound Transmission Class (STC), as described by the American Society For Testing and Materials (ASTM). This rating is calculated by measuring, in decibels, the transmission loss at several frequencies under controlled test conditions and then calculating the single-number rating from a prescribed method. When an actual constructed system is concerned (i.e., where conditions such as absorption and interior volume are not controlled in a laboratory environment), the single-number rating describing the acoustical performance of such a system can be expressed as a field STC rating (FSTC), which approximates a STC rating when tested on-site. The higher the FSTC rating of a constructed system, the greater the transmission loss.
A conventional wall assembly 300 (called a wood stud wall) is shown in FIG. 3 and consists of two gypsum boards 303 (also referred to as drywall or sheetrock skins) attached directly to either sides of wood studs 301. The space between the wood studs 301 may be filled with some type of fibrous insulation 305 (e.g., fiber glass batts). A wall assembly such as assembly 300 generally results in transmission loss values between STC 30 and STC 36, because although the cavity area between the wood studs 301 is filled with sound insulation material 305, sound energy can easily pass through the structural connections between the wood studs 301 and the gypsum boards 303. Accordingly, assembly 300 is generally ineffective in reducing sound energy transmission.
Several methods are currently used by builders to produce wall and ceiling/floor assemblies with higher FSTC ratings than the performance of a basic wood stud configuration. One such method is the use of resilient channels in a wall assembly 400, shown in FIG. 4a. This method involves inserting one or more thin metal channels 407 between one of the drywall skins 403 and framing members 401. The resilient channels 407 act as shock absorbers, structural breaks, and leaf springs, reducing the transmission of vibrations between a drywall skin 403 and the framing members 401. However, the resilient channel technique is difficult to install correctly and requires excessive labor costs. It is very easy to xe2x80x9cshort outxe2x80x9d a resilient channel 407 by improper nailing techniques (e.g., screwing long screws into the wood studs 401 behind the resilient channel 407). When this occurs, the sound isolation of wall assembly 400 remains unimproved. Similarly, problems relating to the difficulty of installing resilient channels may result when the technique is used to sound-isolate floor-ceiling assemblies.
Other current practices involve staggering the positions of wall studs 401 (as illustrated in FIG. 4b) or using double stud construction (as illustrated in FIG. 4c). These methods create a larger cavity depth and can reduce the structural connections between wall assembly components 401 and 403, thereby allowing an assembly 400 to achieve relatively high FSTC ratings. However, both of these methods double the cost of framing and increase the thickness of wall assembly 400 by approximately two to four inches.
In addition, various sound absorbing or barrier materials are currently used to provide a structural break between wall studs or floor-ceiling joists and the boards attached to them. Examples of such materials include GyProc(copyright) by Georgia-Pacific Gypsum Corporation, 440 Sound-A-Sote(trademark) by Homasote and Temple-Inland SoundChoice(trademark). While capable of providing additional sound-transmission loss, these materials are generally dense and heavy, resulting in high handling and installation costs.
Accordingly, what is needed is a wall or floor-ceiling assembly that includes a material between the framing members and building boards either in sheets or strips that can provide additional substantial sound transmission loss, and is both relatively lightweight and easy to install.
The present invention is directed to the installation of a lightweight sound-deadening board in sheets or strips in a wall or floor-ceiling assembly without the need for expensive methods, training, or tools. The lightweight board may be made of compressible material with an optimum range of compressibility. This material may be either non-resilient foam or a resilient non-foam material.
According to a first embodiment of the present invention, a building component assembly is provided comprising at least one assembly framing member, at least one assembly board, and at least one sound-deadening board, wherein the sound-deadening board is made of a substantially non-resiliently compressible material with an optimized compressibility, is positioned between the at least one assembly framing member and the at least one assembly board, and has an Equivalent Young""s Modulus (bulk modulus of elasticity) between 50 and 600 pounds per square inch and a thickness between xc2xc and 1 inch. This value may be achieved through means of basic material properties (true Young""s Modulus), or by the physical alteration of the board to make the modulus appear lower when installed in the described manner. Kerfing, grooving, waffle cuts and boring are all examples of such alterations.
According to a second embodiment of the present invention, a building component assembly is provided comprising at least one assembly framing member, at least one assembly board, and at least one sound-deadening board, wherein the sound-deadening board is made of a substantially resiliently compressible non-foam material with an optimized compressibility, is positioned between the at least one assembly framing member and the at least one assembly board, and has an Equivalent Young""s Modulus (bulk modulus of elasticity) between 50 and 600 pounds per square inch and a thickness between xc2xc and 1 inch. This value may be achieved through means of basic material properties (true Young""s Modulus), or by the physical alteration of the board to make the modulus appear lower when installed in the described manner. Kerfing, grooving, waffle cuts and boring are all examples of such alterations.
According to a third embodiment of the present invention, a method of installing a sound-deadening board in building component assembly is provided, comprising the steps of attaching at least one sound-deadening board to at least one assembly framing member, and attaching at least one assembly board to the at least one assembly framing member and at least one sound-deadening board, such that the sound-deadening board is positioned between the assembly board and the assembly framing member, wherein the sound-deadening board is substantially made of a non-resiliently compressible material with an optimized compressibility, is positioned between the at least one assembly framing member and the at least one assembly board and has an Equivalent Young""s Modulus (bulk modulus of elasticity) between 50 and 600 pounds per square inch and a thickness between xc2xc and 1 inch. This value may be achieved through means of basic material properties (true Young""s Modulus), or by the physical alteration of the board to make the modulus appear lower when installed in the described manner. Kerfing, grooving, waffle cuts and boring are all examples of such alterations.
According to a fourth embodiment of the present invention, a method of installing a sound-deadening board in building component assembly is provided, comprising the steps of attaching at least one sound-deadening board to at least one assembly framing member, and attaching at least one assembly board to the at least one assembly framing member and at least one sound-deadening board, such that the sound-deadening board is positioned between the assembly board and the assembly framing member, wherein the sound-deadening board is substantially made of a resiliently compressible non-foam material with an optimized compressibility, is positioned between the at least one assembly framing member and the at least one assembly board and has an Equivalent Young""s Modulus (bulk modulus of elasticity) between 50 and 600 pounds per square inch and a thickness between xc2xc and 1 inch. This value may be achieved through means of basic material properties (true Young""s Modulus), or by the physical alteration of the board to make the modulus appear lower when installed in the described manner. Kerfing, grooving, waffle cuts and boring are all examples of such alterations.